1. Field of the Invention
The present general inventive concept is directed to an apparatus with manual operation and improved conductivity for temporarily disconnecting an electrical power source and providing for reconnection.
2. Description of the Related Art
Electrical connections are common in industrial applications and in automotive and trucking applications. Electrical power is used in a wide variety of electronic control devices as well in motor vehicles. Often, disconnection of electrical power is needed either to prevent electrical power loss from a battery, or to present a safe condition for a person to perform maintenance without the risk of electric shock, or prevent the operation of the system, such as an automotive engine starting. Also, a manual emergency disconnect is needed. In some cases, the electrical disconnection must be suited for locking such as in a lock-out tag-out or other regulatory requirement to insure that electrical power has been disconnected and cannot be inadvertently reconnected without proper authorization.
Known power disconnection devices include that disclosed in U.S. Pat. No. 4,388,504 to Hruda et al. which discloses a latching mechanism that utilizes hermetically sealed switch assembly and an air or hydraulic cylinder to apply sufficient force to open and close the switch. This pressure is used to provide an unlatching force to flip a conical washer provide switch contact movement. The washer is utilized to flip from convex upward to convex downward in order to maintain switch contact. A battery disconnect is provided in U.S. Pat. No. 5,562,490 which discloses a rotary switch with two contact arms that can be rotated to engage a contact and a conductor rod that can be inserted into the contact arms. A battery pack manual disconnect is provided by U.S. Pat. No. 6,261,123 to Kruger et al. This patent disclosed a turnable handle that must be raised and then turned to connect prongs to receptors to connect an electrical circuit. Other approaches include a pivotal cam lever in U.S. Pat. No. 5,823,808, while U.S. Pat. No. 5,850,909 utilizes a gear and rack to achieve a connection.
It has been found that increased force at a point of separable electrical contact reduces the resistance of the contact and provides increased performance. Experimental data regarding resistance across two pieces of copper bar was obtained with different force loads. Under 20 pounds of force, the resistance was measured at 344 micro ohms. Under 60 pounds of force, the resistance was measured at 240 micro ohms. Under 100 pounds of force, the resistance was measured at 205 micro ohms. Under 140 pounds of force, the resistance was measured at 194 micro ohms. Under 180 pounds of force, the resistance was measured at 185 micro ohms. Increased force reduces resistance and improves the performance of the connection. However, it is difficult to provide sufficient force by hand, and therefore it is difficult to provide a shutoff switch that provides increased performance while still being easy to operate by hand. What is needed is a power shutoff switch that can connect and disconnect an electrical power source by hand without the need for external forces or equipment and that provides high amounts of force in the established or reestablished contact to provide for low resistance and improved electrical performance of the severable electrical connection.